Circular No. 2758 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Cable Address: SATELLITES, NEWYORK Western Union: RAPID SATELLITE CAMBMASS PERIODIC COMET BOETHIN (1975a) The following precise positions have been reported: 1975 UT R. A. (1950) Decl. m1 Observer Feb. 10.41198 1 35 20.10 +14 51 57.2 11-11.5 Urata 10.75491 1 36 50.31 +15 01 50.0 12.0 Mrkos 10.78789 1 36 59.16 +15 02 51.6 " 11.40417 1 39 41.91 +15 20 45.0 11-11.5 Urata 11.74518 1 41 12.03 +15 30 34.3 12.5 Mrkos 11.75144 1 41 13.20 +15 30 43.7 " 12.74205 1 45 35.72 +15 59 00.1 12.5 " 13.81774 1 50 20.00 +16 29 07.2 12 Ferreri 13.82813 1 50 22.74 +16 29 35.5 " 15.40498 1 57 19.42 +17 12 44.6 11-11.5 Urata 15.40833 1 57 20.37 +17 12 49.3 " Mar. 3.17917 3 06 23.30 +23 12 06.2 Giclas 5.06083 3 14 27.62 +23 45 34.1 McCrosky 5.20069 3 15 03.67 +23 47 54.4 Giclas T. Urata (Nihondaira Observatory). 15-cm f/6 reflector. From Nihondaira Obs. Circ. No. 633. A. Mrkos (Klet Observatory) W. Ferreri (Pino Torinese Observatory). Diffuse without nucleus. H. L. Giclas (Lowell Observatory). Measurer: Mary Lou Kantz. R. E. McCrosky (Harvard College Observatory, Agassiz Station). 155-cm reflector. Measurer: C. Y. Shao. Mr. J. E. Bortle, Brooks Observatory, sends the following total visual magnitude estimates, obtained with a 32-cm reflector: Mar. 5.03 UT, 12.5; 6.02, 12.4; 7.02, 12.5; 10.04, 12.6. It is now clear that the comet is a short-period one, but e is larger than indicated in orbit 2 on IAUC 2749, and there has been no recent close approach to Jupiter. The following orbital elements, by B. G. Marsden, satisfy 24 observations Feb. 5 to Mar. 5 within 3" and most of the rough January observations within 2': T = 1975 Jan. 5.964 ET Peri. = 11.544 e = 0.79522 Node = 26.745 1950.0 a = 5.35986 AU Incl. = 5.917 n = 0.079428 q = 1.09761 AU P = 12.41 years 1975 ET R. A. (1950) Decl. Delta r m1 Mar. 9 3 31.20 +24 49.2 1.411 1.407 12.7 14 3 51.99 +25 57.4 19 4 12.24 +26 52.3 1.533 1.494 13.2 24 4 31.87 +27 35.1 29 4 50.84 +28 06.7 1.672 1.586 13.6 Apr. 3 5 09.11 +28 28.2 8 5 26.69 +28 40.7 1.824 1.680 14.1 13 5 43.57 +28 45.3 18 5 59.78 +28 43.0 1.988 1.775 14.5 28 6 30.21 +28 21.1 May 8 6 58.21 +27 40.8 2.336 1.970 15.3 18 7 24.05 +26 47.0 28 7 47.96 +25 43.1 2.695 2.164 16.0 June 7 8 10.17 +24 31.9 17 8 30.93 +23 15.3 3.048 2.357 16.6 m1 = 10.5 + 5 log Delta + 10 log r PERIODIC COMET SCHWASSMANN-WACHMANN 1 Mr. C. Torres, Department of Astronomy, University of Chile, provides the following precise position, obtained by S. Barros and himself at Cerro El Roble. Measurer: M. Wischnjewsky. 1975 UT R. A. (1950) Decl. Apr. 10.40441 21 24 46.90 -16 59 32.3 COMET BRADFIELD (1972 III) Mr. D. Herald, Woden, near Canberra, provides the following precise positions, obtained with a 20-cm reflector: 1972 UT R. A. (1950) Decl. Apr. 17.37097 2 50 30.71 -50 46 19.2 30.39618 5 54 35.63 -39 13 07.0 May 2.39583 6 15 23.93 -36 10 49.4 3.42222 6 25 08.63 -34 35 33.7 6.40625 6 50 15.05 -30 01 11.1 7.41319 6 57 44.53 -28 30 59.8 8.42847 7 04 51.66 -27 02 03.9 11.40486 7 23 25.79 -22 54 50.2 14.40833 7 39 18.17 -19 08 37.6 1975 March 13 (2758) Brian G. Marsden
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